Synthons, linear and Convergent Synthesis, Umpolung of Reactivity - Organic Chemistry - Government Jobs PDF Download

Linear and Convergent Synthesis

• Linear synthesis: Synthesis of target molecule in a linear fashion
• Convergent synthesis: Synthesize two or more fragments and couple them in a later stage to obtain the target molecule
• Consider a synthesis that involves 5 steps with a yield of 90% each, then

Examples

Examples

Examples

Synthesis of Chlorobenzide

Chlorobenzide-used to kill mites and ticks

Synthesis of Cetaben ethyl ester

Cetaben ethyl ester-used to lower blood lipid levels

Synthesis

ICI-D714-Potential Anti-obesity Drug

Synthesis

Synthesis of Ocfentanil

Ocfentanil-opioid painkiller

Synthesis

Synthesis of Fenfluoramine

Fenfluoramine-Neuroactive drug

Synthesis

Synthesis of Nafimidone

Nafimidone-Antiparasitic drug

Synthesis

Synthesis of Atropine Mimic

Atropine mimic

Synthesis

Synthesis of Propranolol

Propranolol-Beta-Blocker, reduces blood pressure

Synthesis

Synthesis of Arildone

Arildone-prevents polio and herpes simplex viruses from ‘unwrapping’ their DNA

Umpolung

- means reversal of polarity

• Carbon atom of the carbonyl group is electrophilic in nature and susceptible to nucleophilic attack
• A reversal of the positive polarity of the carbonyl group to formyl or acyl anion is called Umpolung process.

Example

Carboxylic acids could be made by the addition of a Grignard reagent to carbon dioxide 

carboxylic acids can also make by nucleophilic displacement of halides by cyanides followed by hydrolysis. This is a classical example of Umpolung process.

Acyl anion derived from cyanohydrins

Acyl anion derived from cyanohydrins

Acyl anion derived from 1,3-dithianes